The Aero Precision M4E1 features the enhanced upper receiver with integrated trigger guard and forward assist deletion option, paired with a quality mid-length gas system barrel in a value-leader AR-15 configuration. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 2014, USA Weight: 6.5 oz Overall length: 35" Status: Active Intended use: Tactical, Home Defense, Plinking